On 11 April 2018 at 16:49, Michael Ellerman <patch-notificati...@ellerman.id.au> wrote: > On Tue, 2018-04-10 at 01:22:06 UTC, Michael Ellerman wrote: >> If you build the kernel with CONFIG_RELOCATABLE=n, then install the >> modules, rebuild the kernel with CONFIG_RELOCATABLE=y and leave the >> old modules installed, we crash something like: >> >> Unable to handle kernel paging request for data at address >> 0xd000000018d66cef >> Faulting instruction address: 0xc0000000021ddd08 >> Oops: Kernel access of bad area, sig: 11 [#1] >> Modules linked in: x_tables autofs4 >> CPU: 2 PID: 1 Comm: systemd Not tainted 4.16.0-rc6-gcc_ubuntu_le-g99fec39 >> #1 >> ... >> NIP check_version.isra.22+0x118/0x170 >> Call Trace: >> __ksymtab_xt_unregister_table+0x58/0xfffffffffffffcb8 [x_tables] >> (unreliable) >> resolve_symbol+0xb4/0x150 >> load_module+0x10e8/0x29a0 >> SyS_finit_module+0x110/0x140 >> system_call+0x58/0x6c >> >> This happens because since commit 71810db27c1c ("modversions: treat >> symbol CRCs as 32 bit quantities"), a relocatable kernel encodes and >> handles symbol CRCs differently from a non-relocatable kernel. >> >> Although it's possible we could try and detect this situation and >> handle it, it's much more robust to simply make the state of >> CONFIG_RELOCATABLE part of the module vermagic. >> >> Fixes: 71810db27c1c ("modversions: treat symbol CRCs as 32 bit quantities") >> Signed-off-by: Michael Ellerman <m...@ellerman.id.au> > > Applied to powerpc fixes. > > https://git.kernel.org/powerpc/c/73aca179d78eaa11604ba0783a6d8b > > cheers
Thanks for the cc. I guess this only affects powerpc, given that it is the only arch that switches between CRC immediate values and CRC offsets depending on the configuration.